Due to the destruction and damage caused by insects in the world, increased efficiency of yield and protection from these insects has made the detection of insect infestation critical. Regulatory operations, quarantine operations, and quality control in production and marketing channels requires technology for early, rapid, and foolproof insect detection. In addition these methods must be economical as well as meet the criteria of non destructive testing. Heretofore, detection of hidden infestations of insects and mites has been accomplished by various means including sound, X-rays, chemical reagents, microwaves and nuclear magnetic resonance. However, these foregoing methods are either limited to small sample size, time consuming, not foolproof, prohibitively expensive, or do not meet the requirements for nondestructive testing.
It is known that insects and mites produce carbon dioxide (CO.sub.2) as a result of their respiratory and metabolic processes. However, the quantity of CO.sub.2 produced by an insect per unit time is so small as to be difficult to detect in the presence of naturally present atmospheric CO.sub.2. Small quantities of such insect-produced CO.sub.2 would show up at best only as a slow, long-term drift in baseline under continuous flow testing and would not be suitable for rapid detection applications. Herein lies the uniqueness of the instant invention. The sample chamber is purged with carrier gas and then sealed off for an interval during which the CO.sub.2 emitted by the insect(s) is allowed to build up and reach a concentration sufficient for detection. The gas flow is then set in motion so that the higher CO.sub.2 concentration bolus moves through the detector cell generating a significant, time-synchronous, transient signal above the background levels of the system.
This invention uses alternating intervals of insect CO.sub.2 buildup and purge by a carrier gas to produce an identifiable signal of insect presence. The carrier gas is normally dry air. Use of the invention in no way alters the test material, does not affect the insects, produces no by-products, and in no way pollutes the environment.
The invention can be arranged for use on ships railcars, motor vehicles, trailers, or aircraft; or can be placed outside or in warehouses, grainholding and handling facilities, laboratories, homes, farm areas, military or government facilities whether fixed or mobile, or commercial establishments. The equipment can be operated in either a fixed or portable manner and can be used for local or remote inspection, surveillance, or monitoring in any of these application. It can be operated manually or automatically in any of these applications.